Alfred berthon



(N0 ModeL) A. BERTHON. TELEPHONE TRANSMITTER.

Patented June 9, 1885.

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ALFRED BERTHON, OF PARIS, FRANCE.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 319,5 8, dated June 9,1885.

Application filed November 14, 1884. (No model.) Patented in FranceMarch 22, 1884, No. l-GLlQl, and in England March 4,

reference to that class of battery-transmitters in which granularparticles of conducting material, and specially of carbon, constitutethe variable-resistance medium, they being confined in aloose statebetween a vibratory dia-. phragm and aback plate, both of conductingmaterial, and electrically connecting the dia-' phragm and back platewith each other. 1 The poles of the battery-circuit are connected onewith the diaphragm, the other with the back )late. a v 1 Heretofore insuch transmitters the dia-; phragm and back plate have been made of 5metal, and the conducting particles have beenl retained by the walls ofthe instrument, so thati they cover a large part of the surface of theplate. Heretofore, also, rounded particles or. shot of conductingmaterial havebeen placed in atnbe of non-conducting material at thecenter of the diaphragm and confined between it, or a button carried byit, and aback plate. In one case the tube has been of soft rubber, andattached both to the diaphragm and back 1 plate, in another, of wood,and fastened only to the back plate. 7

The present invention comprises certain novel constructions andcombinations, as follows:

First. A vibratory carbon plate, supported at the edges, constitutes thediaphragm, and the back plate is also made of carbon, the looseparticles of conducting material being confined between and in contactwith said plates in any ordinary or suitable way. The advantage of thecarbon plates in this connection is that a better contact is made,(probably on account of the surface structure of the carbon plate, andif carbon particles are used, as they usually would be, on account alsoof the like nature,)while at the same time vibrations are bettertransmitted than in the case of a carbon 3 "button attached to thediaphragm. A carbon diaphragm is not new in itself, but is new in thecombination stated.

Second. The carbon back plate as well as the carbon diaphragm issupported at the edges so that it is capable of vibrations. It is notnew to employ two vibratory plates supported at the edges in abattery-transmitter; but in all heretofore known the plates have been,so far as I am aware, of metal.

Third. The space behind the back-plate is left open either by omittingthe back of the case or, better, by perforating it with one or moreholes. The latter construction is better because it gives moreprotection to the back plate. I

Fourth. The loose particles of conducting materialare held ina rigid cupof insulating plate, and keeping the particles together in the center ofthe carbon diaphragm with 'which it makes contact. This is found to givebetter articulation than when the carbon partiprobably because thevariable-resistance medium is acted upon only by that part of thediaphragm having the largest vibration. It also has the effect ofincreasing the resistance of the transmitter and diminishing the weightof the mass of particles, and also of lessening the tendency of theparticles to pack.

Fifth. The conducting particles are made of small carbon grains, aboutone millimeter in diameter, more or less, and of irregular shape. Ballsof carbon of two millimeters and over in diameter would not give thesame result. They could, of course, be used in connection with thecarbon back plate and carbon diaphragm, but not advantageously. Thesmall particles of irregular form are advantageous, becausethey give thesame number of contacts with less weight, and because the irregir larityin form gives contacts better suited to telephonic transmission. Thecombination of such particles with a diaphragm, when they are looselyconfined at the center of the diaphragm by a cup, is believed, broadly,to be new, whether the contact be directly with the diaphragm or with abutton carried thereby.

Sixth. In order to leave the conducting parmaterial, supported upon thecarbonrback' *cles extend to the edges of the diaphragm,

ticles perfectly free to move among themselves,

contact with the particles, and irrespective of the material of whichsaid diaphragm or button is made.

Seventh. A'flaring or funnel-shaped cup is used to retain the conductingparticles in the center of the diaphragm. This is advantageous, becauseit allows the particles to fall down more readily against the diaphragmwithout giving too great an inclination to the instrument- It ispreferred to adjust it so that the diaphragm and back plate are inclinedfortyfive'degrees, the inclination of the sides of thefunnel-shaped cupmaking about the same an- .gle with the axis of the funnel.

Eighth. The foregoing elements are combined with one another, thecombination constitutin g an improved transmitti r g-instrument withsundry advantages. Having now ex- .plained the principle of theinvention, what is considered the best mode of applying the same will bedescribed, with the aid of the accompanying drawings, which make a partof this specification.

Figure 1 is a front View, partly in section, of a telephone-stationapparatus provided with a transmitter constructed in accordance with theinvention; Fig. 2, a cross-section of the same; Fig. 3, a diagramillustrating the arrangement of circuits; Fig. 4, a view, half plan andhalf section, of the transmitter 011 an enlarged scale, and Fig. 5 across-section of the transmitter.

A is the box or case of insulating material hard rubber,'for example; B,the carbon back plate; 0, the carbon diaphragm; D, the flaring orfunnel-shaped cup, of rigid insulating material, (hard rubber,) and Ethe mass of loose carbon particles constituting the variable-resistancemedium.

Both plates B O are or may be made in any suitable way of artificialcarbonthat is, of the same composition as that of which the carbons forelectric-arc lamps are made. Practically a cylinder is pressedoutthrough a die, asin making lead pipe. The cylinder is slit and spreadout, and a circular disk is cut by a sharp-edge die. The plates are thenbaked in a furnace. Their thickness is preferably from one and one halfto two millimeters, (1 i to 2 mm.) They are or may be used in thecondition in which theyleave the furnace. The

.mass E is composed of grains or small particles of retort or gascarbon, obtained of equal size by careful sifting. Grains of onemillimeter or less in diameter are suitable. The Weight of the mass E isonly a few centigrammes.

The back plate is supported at the edges by the soft-rubber'ring F,whichalso separates it from the back of the box or case A. The diaphragm orvibratory front plate, 0, is supported at its edges by the ring G, ofsoft rubber, which separates it from the back plate, B. The ring G is ormay be three to three and one-half millimeters (3 to 3% mm.) inthickness. The plates are confined by the screw-ring H, of brass orother material. A soft-rubber ring, I, is interposed between the ring Hand the diaphragm O. The object of using soft-rubber rings is to act ascushions to prevent the can bon of the plates from being crushed inscrewing up the ring H. They also hinder the production of abnormalvibrations in the use of the instruments.

No mouth-piece is used, although one could be employed. Its use is notdesirable, except upon long lines, because while it increases theloudness of the speech transmitted it renders the sounds more strident.

The exterior conductors are connected with the diaphragm and back plateby means of binding-posts permanently in electrical connection, one witheach carbon plate, by a wire, 100 and 101, respectively, say, ofsilver,whose ends are flattened, one end beingconfined between thecarbon plate and the adjacent rubber ring, and the other clamped betweenthe backof the case and the base of the bindingpost.

The flaring or funnel-shaped cup D is fastened at the smaller end to theback plate, B, by gum-arable, gum-lac, or other adhesive material. Thecup has no bottom, so that the carbon particles rest upon the backplate. It is filled, preferably, about five-sixths (g) full, althoughthe exact amount is not essential. It could be filled sojhigh that theparticles make contact with the diaphragm when the instrument ishorizontal,with the diaphragm uppermost; but it is better to leave aspace at the top, so that the particles are left freer to move amongthemselves, and make contact with the diaphragm only when the instrumentis turned more or less on its edge.

The height of cup D is less than the thickness of ring H, so that itdoes not touch the diaphragm G. The latter may, therefore, vibratefreely.

In use the transmitter is tipped at an anglesay, forty-five degrees. Asshown, it is supported at the end of the arm K. In the bottom of the boxA are a number of holes or perforations, Q. The instrument will operatewithout them; but when used they make the transmission stronger.

The arrangements of the station apparatus may be those. in ordinary use,the improved transmitter being'substituted for that in use. As shown,some slight modifications are introduced. The transmitter is included inthe circuit 1 with a battery of, say, one or two cells Leclanch and theprimary wire of an induction-coil, L. The secondary wire of theinduction-coil (being, say, one hundred and fifty ohms resistance) isincluded ina branch, 2, of the main line, which branch includes also thehand-telephones M. The spring-key N, when the latter is on its backcontact, is included in the branch 3 with the signal-bell. (Not shown.)The back contact is, at the end of branch 4, connected with the battery.

WVhen the line is not in use, the hand-telephones hang on the hooks oneach side of the apparatus. The hook on the right forms part of theordinary automatic gravity-switch. Normally, the signal-bell only is incircuit. To signal central office or another station on the sameline,the keyN is pushed in, thus including the battery in the line, andcutting out the bell at the signaling station.

When the telephone is removed from the switch-hook,the bell and key arecut out, the main line is completed through branch 2, and thebattery-circuit l is established through the transmitter.

When one talks before the transmitter, the carbon diaphragm O is throwninto vibrations, which are communicated to the massEof carbon particlesand also to the carbon back plate. The result is a variation in theresistance of the battery-circuit 1, producing corresponding undulationsin said circuit and through the action of the induction-coilin the mainline.

The transmission of the voice is exceedingly strong and clear, withoutirregularity of any nature, no matter whether the words are spoken in ahigh or in a low tone, and whether near the diaphragm or atadistance ofsome centimeters. Ten centimeters distance is the most suitable. It isnot necessary, after a certain time, to shake this transmitter, in orderto renew the contact-surfaces of the grains, but, if shaken, itcontinues to transmit equally well.

Although I have given a detailed description of one of the improvedtransmitters, I do not intend to limit myself to these details, as theycan be varied without departing from the spirit of the invention. Partsalso of the invention can be used separately.

The transmitter could of course be used in the same circuit with abattery and telephone receiver, instead of being connected therewiththrough an induction-coil, although this would not be a desirablearrangement considering the low resistance of the transmitter.

Having now fully described my said invention and the manner of carryingthe same into effect, what I claim is- 1. In a telephonic transmitter,the combination, with avibratory carbon plate supported at the edges anda carbon back plate, of interposed carbon particles loosely confined incontact with said plates, substantially as described.

2. The two carbon plates, both supported at the edges, so as to becapable of vibrating, in combination with the interposed particles ofconducting material, such as carbon,loosely confined in contact wit-hsaid plates, substantially as described.

3. The combination, with the vibratory carbon plate supported at theedges and theloose particles of conducting material, of the carbon backplate supporting the cup of nonconducting material, whereby the looseparticles of conducting material are held in contact with the aforesaidvibratory plate, substantially as described.

4:. The two vibratory plates of carbon supported at the edges, incombination with an interposed medium of high resistance for completingthe circuit between said plates, so as to allow the resistance of suchcircuit to be varied in accordance with the vibrations of said plates,substantially as described.

5. In a telephone-transmitter, and in combination with the vibratorydiaphragm and the conducting particles, the cup of non-conductingmaterial for containing said particles, the same being flaring orfunnel-shaped, substantially as described.

6. The combination, with the vibratory front plate and the back plate,both inclined to the horizontal, of the flaring or funnel-shaped cup ofnonconducting material and the loosely confined particles of conductingmaterial, substantially as described.

7. In a telephone-transmitter, the combination, with the diaphragm andback plate, of a rigid cup attached to the back plate and separated fromthe diaphragm, and the mass mo of loose conducting particles partlyfilling said cup, so that when the instrument is horizontal no circuitis established through the instrument, but when the latter is raised theparticles fall forward and complete the circuit, sub- I05 stantially asdescribed.

8. In atelephone-transmitter, the combination, with the diaphragm, of arigid. cup and the small irregular carbon particles loosely confined insaid cup at the center of the dia- :10 phragm, the said particlesconstituting the variable-resistance medium, substantially as described.

9. The combination of the case having the back open or perforated, thetwo vibratory [15 plates supported at the edges in said case, and thevariable-resistance medium between said plates, substantially asdescribed.

In testimony whereof I have signed this specification in presence of twosubscribing 12o witnesses.

A. BER'JIHON.

Witnesses:

PHILIP MAURO, O. J. HEDRIOK.

